Influence Of Ultrasonic Vibrations Research Articles

Ultrasonic-assisted preparation-forming-curing process for ultra-thin micro-fiber metal laminates: Deformation characteristics

At present, Fiber metal laminates (FMLs) are mostly used in the aeronautical field to manufacture large-size components, such as skins of fuselage or wing. However, the utilization of FMLs in microsystems and micro-electro-mechanical systems has not been explored yet. Therefore, miniaturization of conventional FMLs and integration of micro-sheet preparation and complex-shaped components forming are of utmost significance from a practical viewpoint. Herein, an integrated ultrasonic-assisted preparation-forming-curing method is proposed to manufacture ultra-thin micro-Ti/Cf/PPS hybrid laminates (TA1/Carbon fiber/PPS) components in this paper. The influence of ultrasonic vibrations on the performance of as-prepared micro-laminates is systematically studied, including the immersion distribution of PPS resin in Cf layer, interfacial bonding properties of Cf/PPS and Ti/PPS interfaces and micro-deformation mechanism of metallic layer. Furthermore, the hot bulging test is carried out by rapid transfer of the micro-laminates at melting temperature (280 °C) of the resin layer using a micro-arrayed spherical-cap die to assess the formability. A combination of electron backscatter diffraction (EBSD) analysis, metallographic observations and image precision measurement revealed the unique deformation characteristics and thickness evolution of complex-shaped micro-Ti/Cf/PPS laminates. Overall, a high deformation level is achieved during the bulging process. The current study provides an enhanced understanding of ultrasonic-assisted micro-forming-curing process.

Development and Research of Models and Processes of Formation in Silicon Plates p-n Junctions and Hidden Layers under the Influence of Ultrasonic Vibrations and Mechanical Stresses

In this article, mathematical models and processes of introducing homogeneous ultrasonic oscillations and mechanical stresses into silicon wafers in the direction of their thickness are developed and investigated, and mathematical models of the movement of interstitial defects in silicon wafers created by the processes of ion-beam transients at the transitions of ion-beam transitions and hidden dielectric layers using the action of ultrasound oscillations and mechanical stresses, both in the process of implantation of impurities and before the annealing of plates upon activation of the impurities are developed and investigated.

Ultrasound influence on the physical and mechanical properties of wire at equal-channel angular broaching

The structure of ultrafine-grained materials obtained by deformation methods under the influence of ultrasonic vibrations is investigated; new methods of intense plastic deformation have been developed with the imposition of ultrasonic vibrations, allowing the formation of an ultrafine-grained structure in extended materials; optimal modes of plastic deformation and heat treatment were determined, allowing one to achieve the highest thermal stability and ductility in combination with high strength of materials. The designs of ultrasonic oscillatory systems for obtaining extended bulk nanostructured materials were developed, and a technological scheme of producing an ultrafine-grained wire using ultrasonic processing with equal-channel angular broaching was tested. It is shown that this process of deformation processing is industrially applicable, and can be combined into a single technological cycle with wire drawing. The results can be used in engineering, instrument making and cable industry.

Influence of ultrasonic vibrations on the microstructure and mechanical properties of Al/Ti friction stir lap welds

Abstract Al/Ti dissimilar welds were fabricated by ultrasonic vibrations assisted friction stir welding, which eliminated the tool wear and enhanced the material flow. The peak temperature was lowered, and a pre-heating period was introduced into welding by ultrasonic vibrations. Wider interface and smaller grain structures were observed in the welds due to the reinforced material flows. Ti fragments were spun into the Al alloy, resulting in a mixing zone beside the interface. Atomic diffusion was also enhanced with ultrasonic vibrations, according to the element maps. The strength of the Al/Ti welds was doubled with the influence of ultrasonic vibrations. The fracture was nucleated at the interface and propagated into the base materials. Shear dimple was the dominant characteristic of the fracture morphology, whereas cleavage planes were also found.

Effect of ultrasonic assisted friction stir welding on microstructure and mechanical properties of AZ91−C magnesium alloy

Abstract The influence of ultrasonic vibrations on microstructure and mechanical properties of the AZ91−C magnesium alloy after ultrasonic assisted friction stir welding (UaFSW) in comparison with conventional friction stir welding (FSW) was investigated. The FSW was applied at the rotational speed of 1400 r/min and welding speed of 40 mm/min and no defects were observed. Using the same welding parameters, the process was carried out with inducing ultrasonic vibrations to the weld line at the amplitude of 15 µm. The microstructure of the specimens was observed with optical and scanning electron microscopy. The results indicate that a very fine microstructure is obtained in UaFSW with respect to that of conventional FSW. Moreover, β-Mg17Al12 coarse dendrites are segregated to very fine and partly spherical particles that homogeneously distribute in α-Mg matrix. This remarkably-modified morphology of microstructure attributed to severe plastic deformation comes from ultrasonic vibration and friction stirring effect. Tensile and hardness tests were performed to evaluate the mechanical properties of the welds. According to the results, the vibration greatly improves the mechanical properties of the conventional FSW joint. The tensile strength and hardness are increased from 195 MPa and HV 79 in conventional FSW to 225 MPa and HV 87 in UaFSW, respectively.

The Study of the Influence of Ultrasonic Vibrations on Structural Changes of Steel

The paper describes a cause of the geometric accuracy degradation of slender metallic products during their operation, which consists in the relaxation of residual stresses accumulated while product manufacturing. The most promising technology among the existing technologies of residual stress relaxation is based on the use of vibromechanical vibrations. This technology has high performance and low energy consumption. The reason for the relaxation of residual stresses under the action of vibromechanical vibrations is the gradual accumulation of internal energy, which leads to plastic dislocation shifts upon reaching a critical level. The dislocation motion under the action of vibromechanical vibrations continues until the dislocations take a more compact layout that corresponds to the equilibrium energy state. For technological implementation of the process there was developed a method of ultrasonic stabilization of elastic plates, which serve as sensing elements in differential-pressure transducers. The experimental studies of ultrasonic stabilization are carried out. According to the results of the studies, there have been conducted tests of the microstructure of the control samples. It is established that the samples of steel 20CH13 subject to ultrasonic treatment have a more uniform structure than the samples after the factory technology of long "aging". This confirms the assumption about the structural-energy processes occurring during vibromechanical relaxation of residual stresses. The technology of ultrasonic stabilization can be recommended as a replacement to the "aging" technology on the basis of the obtained results.

The Effect of Ultrasonic Treatment of a Lubricating Oil on the Operation of a Tribological Assembly and the Assessment of the Residual Effects in the Oil

This paper presents the results of a study of the operation of a “roller—pad” friction pair under the influence of ultrasonic vibrations with a frequency of 8–17 kHz on lubricating oil. Further, the surface tension coefficient and the lubricating oil temperature during its processing in the frequency range of 8–43 kHz is evaluated. It has been established that both ultrasonic treatment of lubricating oil and the increase in the frequency of the treatment significantly improve the operating conditions of the friction pair, reducing the linear wear of samples, the rates of the wear of moving and fixed samples of friction pairs and the wear factor number. It has been established that the surface tension coefficient of synthetic motor oil, decreasing to the minimum value during the first 120 h of ultrasonic treatment, is maintained at this level for more than 72 h.

Experimental and numerical study on heat transfer enhancement using ultrasonic vibration in a double-pipe heat exchanger

Heat transfer enhancement of double-pipe heat exchanger in the presence of ultrasonic vibrations is experimentally and numerically studied. A novel experimental setup made of two concentric pipes is constructed and a bolted Langevin ultrasonic transducer is used for applying the ultrasonic vibrations to the inner pipe with a frequency of 26.7 kHz. The numerical simulation is carried out by OpenFOAM software to clarify the reason for heat transfer enhancement. The effects of hot and cold fluid flow rates and acoustic power on heat transfer and pressure drop are studied in this work. The performance of heat exchanger is investigated by comparing the overall heat transfer coefficient and pressure drop with and without the influence of ultrasonic vibrations. Results show that using ultrasonic vibration is more effective at low fluid flow rates. As a result, heat transfer enhances about 60% for both cold and hot fluid flow rates of 0.5 L/min, while heat transfer enhancement is equal to 20% for cold and hot fluid flow rates of 1 and 1.5 L/min, respectively, at the transmitted acoustic power of 120 W. Numerical results demonstrate that the cross-stream flows generated by propagation of ultrasonic waves into the cold fluid are responsible for heat transfer enhancement.

Effect of water-based ultrasonic vibration on the quality of laser trepanned microholes in nickel super-alloy workpieces

Effusion cooling holes are commonly drilled in nickel super-alloy aero-engine components using electro-discharge machining (EDM) or pulsed laser drilling. While drilling quality of EDM is high, its machining efficiency is normally relatively low, in addition to its high tooling cost. The drilling efficiency of a millisecond pulsed laser is much higher, while a recast layer often forms on the hole wall. In this paper, an ultrasonic-assisted laser trepanning technology is reported for trepanning blind and through holes in nickel super-alloy samples. The influence of ultrasonic vibrations on hole geometry, morphology, microstructure, recast layer thickness and mechanical performance was investigated through comparing holes trepanned with and without ultrasonic assistance. It was found that ultrasonic vibrations contributed to laser trepanning process mainly by means of grain refinement strengthening, hard phase precipitation and dispersion strengthening, and led to recast layer reduction and negative taper for the through hole trepanned. The percentage of the measured recast layer reduction induced by ultrasonic vibrations approximately ranged from 15.73% to 31.82%. Besides, a maximum percentage of around 19.43% was achieved for micro hardness improvement induced by ultrasonic vibrations. However, the width of laser trepanned heat affected zone (HAZ) was increased by around 36.00% due to ultrasonic vibration assistance. In addition, the HAZ grains near the recast layer was refined via increasing the trepanning speed, decreasing pulse width. Compared with the base metal, the impact toughness was increased by using ultrasonic-enhanced laser trepanning mainly due to grain refinement strengthening.

Influence of ultrasonic sound on physico-mechanical characteristics of titanium alloys

The paper presents data on the influence of ultrasonic vibrations on the main physico-mechanical characteristics in the hardening of titanium alloys. Hardening was carried out during rolling and using free balls in a special working chamber with the imposition of ultrasonic vibrations. The studies have shown that ultrasonic hardening of titanium alloys promotes crushing blocks of mosaic and the formation of a fine-grain structure with a high density of dislocations, changes the phase composition of the surface layer and causes the formation of compressive residual stresses. At the same time, technological heredity is practically not manifested. The endurance range of titanium alloys increases.

Sedimentation of suspended solids in ultrasound field

Physical and chemical effects of aquatic environment that occur in an ultrasonic field change the sedimentation rate of coagulated suspension. This might only happen in case of cavitation of ultrasonic filed that causes a change of potentials of the medium. Research of the influence of ultrasonic vibrations on coagulation of suspended solids within water purification allows expanding their scope of implementation. The objective of the research is to estimate the effect of ultrasound on the sedimentation of the suspended solids, to determine of the efficiency of the process in relation to the dose of the coagulant, and to calculate the numerical values of the constants in the theoretical equation. The experiment condition was held in the water with the clay substances before the introduction of the coagulant. The method of magnetostriction ultrasonic generator was applied to receive ultrasonic vibration. Estimate of concentration of clay particles in water was performed using photometry. As a result of the research, the obtained data allow determining the increase in efficiency of suspended particles sedimentation related to the dose of coagulant, depending on time of ultrasonic treatment. The experiments confirmed the connection between the effect of sedimentation in the coagulation process, the coagulant dose and the time of scoring. Studies have shown that the increase in the duration of ultrasonic treatment causes a decrease of administered doses of coagulant.

AUTOMATIC CONTROL OF THE ORE SUSPENSION SOLID PHASE PARAMETERS USING HIGH-ENERGY ULTRASOUND

Context. The authors have solved the urgent problem of controlling automatically the parameters of solid ore suspension aimed for conversion thus increasing the end product quality and facilitating the choice and adhearance to the concentration specifications. Objective. The research aims at developing the method of obtaining operational data as to iron ore characteristics while concentrating, namely distribution of solid pulp particles as to their sizes and estimated grade applying multi-channel ultrasonic measurements. Method. In order to solve the problem of controlling automatically the parameters of solid ore suspension, the authors suggest the method of measuring the intensity of high-frequency bulk ultrasonic waves covering a fixed distance in a measuring chamber containing ore suspension under the influence of ultrasonic vibrations and in case of their absence. The calculated correlations of the measured values make it possible to determine the parameters of solid ore suspension. Besides, while measuring we can observe the formation of gamma-radiation and low-frequency bulk ultrasonic waves in the ore suspension flow. It is possible to measure the intensity of gamma-radiation and lowfrequency bulk ultrasonic waves covering the fixed distance if the measuring chamber contains some reference fluid and the ore suspension flow under ultrasonic vibrations and in the absence thereof. The intensity of ultrasonic vibrations influencing the suspension flow is changed according to the relevant law. Results. The dynamic effects of high-frequency ultrasound provide a theoretical basis and a practical approval of the method controlling the solid phase of iron ore pulps in order to displace the particles of the required grain-size class to the measuring zone and to determine the grade in ore particles. The developed purpose-designed programme realizes a numerical analysis and graphical representation of simulation results of changing solid pulp particle-sizes under the controlled influence of high-energy ultrasonic radiation pressure. Conclusions. The authors have devised the method for controlling the distribution of the grade in crushed ore particle-size classes in the pulp flow by means of measuring the changes in the distribution parameters of high- and low-frequency ultrasonic waves as well as gamma-radiation. The method is different from the existing ones by the fact that in the course of measuring, the crushed ore particles of the required size and density are displaced to the measuring zone by exposing the pulps to the high-energy ultrasound influence thus increasing the measurement accuracy by 0.76%.

Influence of ultrasonic excitation on the mechanical characteristics of SLM 304L stainless steel

Selective laser melting (SLM) is a layer by layer powder bed additive manufacturing process that can be used to create high complexity parts. Stainless steel 304L is a material which can be used in a wide range of applications including medical, aerospace, and automotive industries due to its high corrosion resistance. These same industries are also the first users of SLM and research into the combined use of the two can provide benefits for both. Ultrasonic excitation in casting has shown to decrease grain size due to the effect of the oscillating pressure waves on the nucleation conditions. While ultrasonic excitation has been used the solidifying of metals made through casting, it has not been used before in the SLM process. An investigation on the effect of ultrasonic excitation was conducted on the mechanical properties of the material. The characteristics compared were nanohardness, Young’s Modulus, and the anisotropic behavior of said properties. Given that the nucleation conditions were altered, the microstructure was affected by the pressure waves and offset columnar grains development which are formed due to the axial heatsink into the substrate, and thus ensuring a more homogenous development of grains. Given enough power, ultrasonic vibrations should ensure a more even distribution of grains and a reduction of columnar grains. These in term resulted in a reduction of anisotropic behavior, and an increase in nanohardness. The study compared samples made both with and without the ultrasonic excitation applied, as well as with different orientations for anisotropy analysis. A potential improvement in mechanical properties under the influence of ultrasonic vibrations could lead to wider acceptance of the SLM process. Further improvements, such as eliminating the need for thermal post processing could further increase the usability of the technology and 304L as a cheap material for SLM.

Experimental and finite element analysis of ultrasonic vibration−assisted continuous-wave laser surface drilling

ABSTRACTIn pulsed laser drilling with co-axial assisted gas, material removal mechanism (surface vaporization and melt expulsion) determines the machining/drilling rate and quality of the drilled holes. Incomplete melt expulsion is one of the major causes of laser drilling defects. To improve the drilling efficiency and quality of holes, a novel ultrasonic vibration−assisted continuous-wave laser drilling (UVLD) approach is proposed. The application of ultrasonic vibrations (of frequency of 20 kHz and vibration displacement of 23 µm) during laser surface melting facilitates the melt expulsion in the form of sideways melt flow and droplet ejection from the drilling front. A systematic experimental study on the ultrasonic vibration-assisted laser drilling of AISI 316 stainless steel is performed to investigate the effect of working distance on the geometric features and surface quality of the holes. The experimental results based on high-speed photography indicate that the melt expulsion under the influence of ultrasonic vibrations initiates after the laser melted pool reaches a critical size/volume. Based on this underlying mechanism, a simplified finite element analysis is performed for the UVLD process to predict the hole volumes for the investigated working distances.

Influence of ultrasonic vibrations on process performance of electrochemical honing

Electrochemical honing (ECH) is a novel variant of hybrid machining processes (HMPs). The key feature is that the distinct coupling of electrochemical machining (ECM) and honing provide a controlled functional surface generation and faster material removal rate in a single operation. In the present study, the influence of ultrasonic vibrations on process performance of ECH of bevel gears made of EN8 is investigated. An analysis of the process has been presented with suitable illustrations. Ultrasonic frequency and processing time were considered as the input variables while improvement in surface finish, material removal and geometrical accuracies were considered as the monitored output. The effectiveness of the process was investigated through experimental trials by conducting a comparison study between classical ECH and ultrasonic vibration-assisted ECH (UECH). The results confirm that improvements in surface roughness and martial removal rate are significantly higher than those obtained with classical ECH. The study further reveals that the scrubbing of the oxide layer is easier to be achieved and surface quality is obviously improved due to ultrasonic vibrations. The experimental results demonstrate that UECH gives 18.36 % improvement in average roughness, 9.31 % improvement in maximum roughness and 20 % improvement in material removal rate as compared with ECH.

Change in characteristics of superplastic deformation of the aluminum–lithium alloy under the effect of ultrasonic vibrations

The tension of samples of aluminum–lithium alloy 1420 in the superplasticity temperature region T = 320–395°C and the influence of ultrasonic vibrations on deformation characteristics have been investigated. It has been shown that the effect of ultrasound manifests itself in a decrease in resistance to deformation and an increase in total strain. The tension curves plotted in the coordinates true stresses–true strains, in contrast to the standard stress–strain curves, have an extended hardening region, the magnitude of which is larger for the samples deformed with the ultrasound. The stress-rate sensitivity coefficients m have been determined from stress jumps with variations in the tension rate. It has been shown that the quantity m can be assumed to be constant over the entire superplasticity temperature region for different strains with ultrasound and without it, m = 0.46 ± 0.04, and, correspondingly, the stress exponent in the formula for the strain rate is = 2.21 ± 0.23. The activation energies of the deformation process have been evaluated, and it has been concluded that the dislocation motion during the intragrain deformation that is characteristic of the hardening stage is facilitated under the effect of ultrasound.

Laser surface melting of Ti–6Al–4V under the influence of ultrasonic vibrations

Ti-alloys are becoming increasingly important in several manufacturing sectors due to their high strength-to-weight ratio and excellent corrosion resistance. However, surface modification of the Ti-alloys is often required to improve surface hardness and wear resistance. In this paper, laser surface melting (LSM) of Ti–6Al–4V alloy under the influence of ultrasonic vibrations (20kHz) is investigated. The development of microstructure and microhardness in the resolidified region with and without the application of simultaneous ultrasonic vibrations is discussed. It has been observed that the application of ultrasonic vibrations entirely eliminated the large columnar grains from the resolidified region and refined the microstructure, resulting in about two-fold increase in the surface microhardness. The microstructural refinement with the application of ultrasonic vibrations during LSM seems to be primarily due to enhanced fluid flow and cavitation in the melt.

Influence of Ultrasonic Vibrations on Shape Memory Effect

The results of studies on the influence of ultrasonic vibrations (UVs) on shape memory effect (SME) in NiTi alloys are presented. The appearance of shape memory effect is due to changes in the temperature and mechanical stress. They can operate simultaneously under the ultrasonic treatment. It has been found that the ultrasonic vibrations can initiate shape recovery processes in a material with shape memory effect. The reversion of the accumulated deformation occurs at the direct and reverse martensite transformations under the influence of ultrasonic vibrations. Since the process is accompanied by ultrasonic heating, small thermal mechanical hysteresis loops have been observed during the direct transformation. The deformation reversion can be explained by ultrasonic heating of the sample due to the dissipation of vibrations and the formation of austenite.

Self-Propagating High-Temperature Synthesis in the Ti–C–Ni–Mo System on Application of Powerful Ultrasound

An experimental setup has been developed and a study has been made of the self-propagating high-temperature synthesis in a Ti–C–Ni–Mo system under the conditions of action of ultrasonic vibrations. The influence of the amplitude of ultrasonic vibrations on the combustion rate and temperature and on the phase composition and structure of the derived composite material based on titanium carbide with a metal binder has been determined. The heat-transfer coefficient on the surface of a sample for vibrations at ultrasound frequency has been evaluated. Consideration has been given to possible mechanisms of influence of ultrasonic vibrations on the process of self-propagating high-temperature synthesis. It has been shown that the reduction in the synthesis temperature is due to the cooling of the sample because of the forced convection of the surrounding gas, whereas the change in the structure of the synthesized material is related to the change in the conditions of high-temperature heterogeneous interaction in the wave of self-propagating high-temperature synthesis.

Influence of ultrasonic vibrations on side milling of AISI 420 stainless steel

Characteristics of one-dimensional ultrasonic-assisted side milling of AISI 420 stainless steel have been investigated in this paper. Cutting force in ultrasonic-assisted milling (UAM) has been modeled, and new relations for critical cutting speed and undeformed chip thickness have been presented. Based on analytic relations, it can be inferred that in successive end mill revolutions, contrary to conventional milling (CM), cutting forces in UAM have different magnitudes. In order to experimentally investigate the cutting forces and the workpiece surface roughness, CM and UAM processes have been applied and compared in certain cutting conditions. Experimental results indicate that the average of cutting forces in UAM is less than in CM, and depending on cutting parameters, workpiece surface roughness in UAM can improve. During small value of feed, the influence of ultrasonic vibrations on the decrease of cutting forces is more noticeable in up milling, while during larger feed, employing UAM is more effective in down milling. It seems that for low feed rates, high cutting speeds and up milling process, the effect of ultrasonic vibrations on the surface roughness is more noticeable.